Tissue distribution of deoxyribonuclease I (DNase I) activity level in mice and its sexual dimorphism

The distribution of deoxyribonuclease I (DNase I) in mouse tissue and body fluids, the effects of sex on the enzyme activity, and the postnatal developmental regulation of the enzyme were examined in C3H/He mice. DNase I activity was high in the salivary gland and urine; and moderate in the liver, kidney, spleen, preputial gland and seminal vesicle. Weak activity was detected in the pancreas, heart, lung, brain, small intestine, thymus, coagulating gland and serum. Sexual dimorphism, of which males had significantly higher activity than females, was observed in the kidney, urine and liver. This sexual dimorphism in renal DNase I activity was eliminated by gonadectomy to males and testosterone treatment to females. These results reveal sex hormonal control of DNase I production in the kidney. DNase I activity in the liver of infant mice was almost equivalent to that of adult mice while the enzyme activity in the salivary gland, kidney and spleen remained at a low level; less than 5% at one week old and less than 20% at four weeks old. These results suggest tissue specific control of DNase I activity levels during postnatal development.